Optical conductivity of superconducting K{0.8}Fe{2-y}Se2 single crystals: Evidence for a Josephson-coupled phase

Abstract

The optical properties of the iron-chalcogenide superconductor K{0.8}Fe{2-y}Se2, with a critical temperature Tc = 31 K, have been measured over a wide frequency range in the a-b planes above and below Tc. The conductivity is incoherent at room temperature, but becomes coherent (Drude-like) at T ~ Tc; however, R_\Box ~ 64 k-Ohm, well above the threshold for the superconductor-insulator transition at R_\Box = h/4e^2 ~ 6.9 k-Ohm. Below Tc, the superfluid density ρ_{s0} ~ 48 x 10^3 cm^{-2} places this material on the scaling line ρ_{s0}/8 ~ 4.4 σ_{dc} Tc, but in a region associated with Josephson coupling, suggesting this material is inhomogeneous and constitutes a Josephson phase.

Final version, 5 pages, 4 figures and 1 table

References in corpus (14)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• Superconductivity in iron-based F-doped layered quaternary compound Nd[O1-xFx]FeAs
• Superconductivity close to magnetic instability in Fe(Se1-xTex)0.82
• Heavily electron-doped electronic structure and isotropic superconducting gap in AxFe2Se2 (A=K,Cs)
• Coexistence of the spin-density-wave and superconductivity in the (Ba,K)Fe2As2
• Nanoscale phase separation in the iron chalcogenide superconductor K0.8Fe1.6Se2 as seen via scanning nanofocused x-ray diffraction
• Superconductivity at 32K and anisotropy in Tl0.58Rb0.42Fe1.72Se2 crystals
• Strong nodeless pairing on separate electron Fermi surface sheets in (Tl, K)Fe${}_{1.78}$Se${}_2$ probed by ARPES
• Intrinsic phase separation in superconducting K0.8Fe1.6Se2 (Tc= 31.8 K) single crystals
• Optical properties of the iron-arsenic superconductor BaFe1.85Co0.15As2
• Cation vacancy order in the K0.8+xFe1.6-ySe2 system: five-fold cell expansion accommodates 20% tetrahedral vacancies
• 77Se NMR Investigation of the K(x)Fe(2-y)Se(2) High Tc Superconductor (Tc=33K)
• Optical conductivity of superconducting Rb2Fe4Se5
• An inhomogeneous Josephson phase in thin-film and High-Tc superconductors

Cited by in corpus (16)

• The Unexpected Properties of Alkali Metal Iron Selenide Superconductors
• Spin fluctuations in iron pnictides and chalcogenides: From antiferromagnetism to superconductivity
• Orbital-selective metal-insulator transition and gap formation above Tc in superconducting Rb1-xFe2-ySe2
• Optical conductivity of iron-based superconductors
• Macroscopic phase segregation in superconducting K0.73Fe1.67Se2 as seen by muon spin rotation and infrared spectroscopy
• (PI,0) antiferromagnetic spin excitations in superconducting Rb0.82Fe1.68Se2
• Spin-Lattice Coupling in K0.8Fe1.6Se2 and KFe2Se2: Inelastic Neutron Scattering and ab-initio Phonon Calculations
• Effective medium approximation and the complex optical properties of the inhomogeneous superconductor K_{0.8}Fe_{2-y}Se_2
• Correlated disorder to order crossover in the local structure of K${}_x$Fe${}_{2-y}$Se${}_{2-z}$S${}_z$
• Structural phase transition below 250 K in superconducting K${}_{0.75}$Fe${}_{1.75}$Se${}_2$
• Electron-phonon coupling in the superconducting single crystal Rb${}_{0.8}$Fe${}_{1.68}$Se${}_2$
• Tuning orbital-selective correlation effects in superconducting Rb${}_{0.75}$Fe${}_{1.6}$Se${}_{2-z}$S${}_z$
• Suppression of the antiferromagnetic order when approaching the superconducting state in a phase-separated crystal of K${}_x$Fe${}_{2-y}$Se${}_2$
• Optical Properties of Superconducting K${}_{0.8}$Fe${}_{1.7}$(Se${}_{0.73}$S${}_{0.27}$)${}_2$ Single Crystals
• Phase separation in iron chalcogenide superconductor Rb0.8+xFe1.6+ySe2 as seen by Raman light scattering and band structure calculations
• Optical Properties of Iron-Selenide Na${}_{0.27}$K${}_{0.27}$Rb${}_{0.27}$Fe${}_{1.7}$Se${}_2$ Single Crystals